Research Interests

Nanotechnology

Synthesis and assembly of nanoscopic building blocks

Molecular tailoring of interfaces and thinfFilms

Proessing and microanalytical techniques

Professor Ramanath's current research interests are in the areas of synthesis, assembly, and characterization of nanostructures and thin films, with emphasis on exploring new materials and architectures for fabricating future nanodevices for computing, energy generation and management, and understanding the relationships between atomic-level structure and chemistry, and properties. Below are synopses of current topics being pursued in his group.

Directed synthesis and assembly of nanoscopic building blocks and heterostructures: The underlying theme here is to devise strategies to synthesize nanostructures of desired dimensionalities by scalable methods, and construct larger scale architectures in a controllable fashion by combining chemical and/or physical guidance (molecular templating, lithography, ion irradiation, microwave stimulation etc.) with self-assembly. We study the molecular/atomic-level mechanisms by utilizing a combination of multiple electron microscopy, diffraction and spectroscopy techniques. We probe and understand the relationships between structure, chemistry with electrical, magnetic, thermoelectric and mechanical properties, and sensory responses. Examples of structures being investigated include oriented nanotube architectures, branched nanowires, nanorods, and porous networks, one- and two-dimensional assemblies of high-coercivity nanomagnets, core-shell and branched structures of high-figure of merit thermoelectrics, interpenetrating proximal nanowire networks of high- and low-bandgap seminconductors for solar cell applications.

Molecularly tailored interfaces and thin films: The goal of this thrust is to understand processing-stability-property relationships and atomistic/molecular-level mechanisms of thin film interfacial reactions and phase formation during growth (e.g., sputter-deposition, CVD, self-assembly) and post-deposition treatments and relate them to key film and interfacial properties. Topics explored in the past include thin film microstructure evolution and interfacial reactions. The current focus is on investigating the use of self-assembled molecular nanolayers at the interfaces of thin films and nanostructured assemblies as chemical isolators, physical spacers, and adhesion enhancers, and creating molecularly-passivated materials. We are integrating diffusion-inhibiting and adhesion-enhancing molecules with precursors of porous materials to create high interface integrity materials for use as low-k dielectrics in devices. Our studies include quantitative measurements of diffusion barrier properties, mechanical toughness, coverage, electrical characteristics, reliability, and thermal stability of metal-dielectric interfaces and molecularly-tailored porous materials. We are also exploring strategies to directly reduce metal salts directly using termini of molecular assemblies incorporated inside porous materials to obtain a high loading of nanoparticles of controlled shapes/sizes in porous matrices to add a new component to our directed synthesis efforts.